Modeling the Optical Responses of Noble Metal Nanoparticles Subjected to Physicochemical Transformations in Physiological Environments: Aggregation, Dissolution and Oxidation

Abstract

Herein, we study how optical properties of colloidal dispersions of noble metal nanoparticles (Au and Ag) are affected by processes such as aggregation and oxidative dissolution. The optical contributions of these processes to the extinction spectra in the UV-vis region are often overlapped, making difficult its interpretation. In this regard, modeling the UV-vis spectra (in particular absorbance curve, peaks position, intensity and full width at half maximum -FWHM) of each process separately offers a powerful tool to identify the transformation of NPs under relevant and complex scenarios, such as in biological media. The proper identification of these transformations is crucial to understand the biological effects of the NPs.

Assessment of iron oxide nanoparticle ecotoxicity on regeneration and homeostasis in the replacement model system Schmidtea mediterranea

“…Total RNA quantified with a Nanodrop 2000 (Thermo Fisher, Dreieich, Germany) was re-ical reactivity, surface charge, aggregation, or disaggregation, which ultimately determines their potential toxic effects. A significant number of biological systems are complex aqueous media composed of electrolytes, proteins, and metabolites, which can interact with the inorganic surface of the NPs, promoting different physicochemical transformations that modify their biological effects and may ultimately lead to unexpected (including adverse and toxic) effects (Piella et al, 2017;Reidy et al, 2013). The extent of the reactions of NPs is determined by their intrinsic properties (material, size, shape, concentration, crystallinity, surface charge, and coating) and the medium in which they are dispersed (ionic strength, pH) (Piella et al, 2017).…”

“…A significant number of biological systems are complex aqueous media composed of electrolytes, proteins, and metabolites, which can interact with the inorganic surface of the NPs, promoting different physicochemical transformations that modify their biological effects and may ultimately lead to unexpected (including adverse and toxic) effects (Piella et al, 2017;Reidy et al, 2013). The extent of the reactions of NPs is determined by their intrinsic properties (material, size, shape, concentration, crystallinity, surface charge, and coating) and the medium in which they are dispersed (ionic strength, pH) (Piella et al, 2017). Many NPs are unstable and tend to form aggregates after exposure to cell culture media, which modifies the effects they have on biological systems as it influences their reactivity and bioavailability.…”

“…Many NPs are unstable and tend to form aggregates after exposure to cell culture media, which modifies the effects they have on biological systems as it influences their reactivity and bioavailability. Owing to the higher percentage of surface atoms and the colloidal form, NPs acquire a more stable thermodynamic state at a faster time scale than their bulk counterparts (Bastús et al, 2012;; in turn, this translates into higher rates of aggregation, oxidation, dissolution, and interaction with proteins (Liu and Hurt, 2010;Mudunkotuwa and Grassian, 2011;Piella et al, 2017;Reidy et al, 2013;Wang et al, 2014). Therefore, the size distribution profile of the IONs was also determined after incubation in PAM, the medium in which planarians are kept.…”

Nanosafety: Towards Safer Nanoparticles by Design

“…[97] Other approximations have included modelling studies of NP surface interactions with other NPs and proteins, with the aim of understanding the formation process of the PCs or NP aggregates. [98] In all cases, these analyses have to be designed to incorporate and compare the available data for rationalization. Undoubtedly, the development of systematic exposure protocols and reliable methods for assessing NP internalization and their kinetics in living organisms may allow a full description of the exact nature of NP toxicity in the near future.…”

Seeded-Growth Aqueous Synthesis of Colloidal-Stable Citrate-Stabilized Au/CeO2 Hybrid Nanocrystals: Heterodimers, Core@Shell, and Clover- and Star-Like Structures

“…Although the limitations of the Mie theory, especially for small NC sizes, the good correlation between experimental results and Mie calculations confirms the working hypothesis, that is, the possibility of precisely controlling the strongly enhance local electromagnetic fields near the metal-dielectric interface by adjusting Au core size, and CeO2 shell thicknesses. 46 For citrate-stabilized Au NCs, a shell thickness of 0.7 nm and RI=1.3735 was used (Supporting Information, section 15). Results reveal the higher sensitivity of the smaller NCs in comparison with the larger sizes for a determined CeO2 shell thickness.…”